Advances in shoulder arthroscopy and imaging modalities continue to increase our understanding and ability to treat rotator cuff injuries. Partial-thickness rotator cuff tears represent a spectrum of disease states. They can be articular-sided, bursal-sided, intratendinous, or a combination.1 In 1934, Codman described partial tears of the rotator cuff as “rim rents” and recognized that these rim frequently occurred on the articular and bursal surfaces, as well as within the intrasubstance of the rotator cuff.2 Ellman subsequently developed a classification scheme based on the location and depth of these tears.3 Rotator cuff avulsion fractures represent rare lesions which occur mostly in young individual and are caused by trauma.4 Millstein and Snyder later coined the term “PASTA lesion” to describe the partial articular supraspinatus tendon avulsion type injury.5 An even less common variant of this injury is the bony PASTA lesion or partial articular bony avulsion of the supraspinatus tendon (PABAST) described by Bhatia et al.6 There have been numerous arthroscopic techniques described to address this lesion.7 However, we report 2 rare cases of intratendinous avulsion of the supraspinatus footprint with an intact articular and bursal-sided tendon insertion.
CASE REPORT AND SURGICAL TECHNIQUE
A 30-year-old male patient sustained an injury to his left nondominant shoulder while playing football 9 months previously. He had been seen in Peru where he was treated conservatively, and he had an injection into the glenohumeral joint and subacromial space which had no significant benefit. Radiographic examination of the shoulder was unremarkable (Fig. 1). Magnetic resonance imaging (MRI) arthrogram of the shoulder suggested a substantial intrasubstance supraspinatus tear with avulsion of the central portion of the middle third fibers of the supraspinatus from the greater tuberosity attachment. The articular surface of supraspinatus remained in continuity (Figs. 2A, B). No other significant findings.
Arthroscopic examination of the glenohumeral joint was performed with the patient under anesthesia, in the beach-chair position by use of a 30-degree arthroscope through a standard posterior portal and an arthroscopic pump maintaining pressure at 30 mm Hg. The articular-sided deep surface of the supraspinatus tendon was visualized to be intact and no evidence of tear (Fig. 3A). Subacromial space showed abnormal contour of the lateral margin of the footprint but no superficial rotator cuff tear or evident mobile tuberosity fragment (Fig. 3B). The localization is performed by palpation of the footprint from the bursal surface, when irregularity and some mobility may be felt. This is in combination with measuring the avulsion from the anterior supraspinatus on imaging. No other pathology was visualized in the glenohumeral joint or subacromial space.
The lateral tuberosity was debrided, tendon explored, and bursectomy performed. A single bioabsorbable 5.5 mm screw anchor was implanted to the calculated center of bony avulsion and 2 simple suture tension band repair of anterior and posterior columns of the supraspinatus avulsion. A stable repair construct was obtained (Fig. 4).
The postoperative protocol consisted of Polysling immobilization for 6 weeks. Passive range of motion (ROM) exercises allowed from 2 weeks after surgery with external rotation at the side and elevation in the scapular plane to the horizontal progressing as patient comfort allows. Active full range of motion allowed from 6 weeks. At 3 months postsurgery, almost full ROM and function of shoulder were reached. Oxford Shoulder Score improved significantly from 34 (preoperative) to 43 postoperatively at 3 months.
A 37-year-old lady presented for a second opinion regarding her left shoulder. She had sustained a skiing injury 9 months previously. She was initially treated conservatively with physiotherapy, but her symptoms persisted. Her initial MRI scan (Fig. 5A) 3 weeks following injury showed nondisplaced greater tuberosity avulsion with an intact rotator cuff. Repeated MRI scan (Fig. 5B) after 6 months has shown an apparent nonunion of the greater tuberosity fragment but no displacement.
Arthroscopic examination of the injured glenohumeral joint was performed with the patient under general anesthesia, in the beach-chair position by use of a 30-degree arthroscope through a standard posterior portal and an arthroscopic pump maintaining pressure at 30 mm Hg. The articular-sided deep surface of the supraspinatus and infraspinatus tendon footprint were intact with no evidence of tear (Fig. 6A). The subacromial space showed significant active bursitis with abnormal contour of the lateral aspect of supraspinatus, but no rotator cuff tear or evident mobile tuberosity fragment (Fig. 6B). No other pathology was visualized in the glenohumeral joint or subacromial space. The localization is performed by palpation of the footprint from the bursal surface, when irregularity and some mobility may be felt. No elevation or debridement to the lesion was performed.
The lateral aspect of the supraspinatus footprint was debrided to healthy greater tuberosity bone. One absorbable threaded anchor implanted to the calculated center of the avulsion fragment. A simple 2 suture tension-band repair of the superior lamina of the tendon was performed to create compression and equalize tension on footprint. A routine subacromial decompression was performed with release of the coracoacromial ligament, anterior acromioplasty, and subtotal bursectomy.
The postoperative protocol consisted of Polysling immobilization for 6 weeks. Passive ROM exercises allowed from 2 weeks after surgery with external rotation at the side and elevation in the scapular plane to the horizontal progressing as patient comfort allows. Active full ROM allowed from 6 weeks. At 3 months postsurgery, almost full ROM and function of shoulder were reached. CT scan (Figs. 7A, B) at 3 months postsurgery confirmed that avulsion fracture had healed and correct placement of suture anchor.
Rotator cuff pathology is one of the most common conditions evaluated and treated by the practicing shoulder surgeon. Avulsion fracture of the rotator cuff footprint is an uncommon and frequently missed diagnosis. Mistreated and unrecognized, these fractures can cause chronic pain and diminished shoulder range of movement and function. A clear consensus regarding classification and therapy does not yet exist. However, to our knowledge, there is no published report on the treatment of intratendinous avulsions of the supraspinatus footprint with intact articular and bursal attachment of the tendon. Unlike the natural progression of attrition rotator cuff tears, avulsion lesions are often associated with a traumatic event and present acutely.1 Nonoperative management of this injury may be unsuccessful due to the forces applied to the bony fragment by the attached rotator cuff tendon or the immobilization necessary for bony healing.5 Murena et al had reported arthroscopic treatment technique for Bony PASTA lesion7 and Kim and Ha8 report a retrospective case series of 23 patients with minimally displaced or nondisplaced fracture of the greater tuberosity who underwent arthroscopic treatment.
In our report, both patients had a nondisplaced intratendinous avulsion fracture of the greater tuberosity with an intact rotator cuff, had undergone prolonged rehabilitation and had failed nonoperative treatment. Although we do not know the percentage of patients with nondisplaced greater tuberosity fractures who also have an intact rotator cuff, we believe that at least some of these patients will fail nonoperative management. We believe that the advantages of this repair technique include compression of the bony fragment and rotator cuff, allowing restoration of the supraspinatus footprint, creating a waterproof reduction of the fragment and stabilising the fragment to allow union.
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6. Bhatia DN, de Beer JF, van Rooyen KS. The bony partial articular surface tendon avulsion lesion: an arthroscopic technique for fixation of the partially avulsed greater tuberosity fracture. Arthroscopy. 2007;23:786.e1–786.e6.
7. Murena L, Canton G, Falvo DA, et al. The “double-pulley” technique for arthroscopic fixation of partial articular-side bony avulsion of the supraspinatus tendon: a rare case of bony PASTA lesion. Arthrosc Tech. 2013;2:e9–e14.
8. Kim SH, Ha KI. Arthroscopic treatment of symptomatic shoulders with minimally displaced greater tuberosity fracture. Arthroscopy. 2000;16:695–700.